5.9 Production failure catalog for this chapter

Production failure catalog

0 rows

Symptom	Underlying mechanism
A field silently disappears after an edit	Unknown-field loss during a rolling upgrade (§0)
Large IDs are wrong by a few digits in the browser	2⁵³ — JSON number parsed as an IEEE 754 double
RCE from a "harmless" data endpoint	Deserializing a language-native format from untrusted input
Decoding produces garbage after a schema change	Reused Protobuf tag number
Big values truncated after widening a type	Old code still holding a 32-bit variable
"Set to zero" indistinguishable from "not set"	proto3 default-value ambiguity
Every consumer breaks at once after a producer deploy	Added an Avro field without a default
Nothing can decode after a registry outage	Schema registry is on every consumer's critical path and unbacked-up
Old readers break after a field rename	Rename is backward but not forward compatible in Avro
gRPC traffic all lands on one backend	HTTP/2 multiplexing vs an L4 load balancer
Server burns CPU on abandoned requests	Deadline not propagated
Duplicate side effects after a retry	Timeout gave no information; no idempotence in the protocol
Deprecated API version can never be removed	No per-version usage instrumentation; no control over clients
Fields dropped as messages pass through a pipeline	Consumer republished after decoding into an old model
Workflow throws `NonDeterministicError` after a deploy	Reordered or added activity calls, breaking replay
Payment charged twice	Third party not idempotent, no idempotency key
Clients see stale IPs after a failover	DNS caching used for a dynamic service population